Ti5Si1.3Sb1.7 — The first titanium silicide antimonide, forming a crystal structure not found in either binary system

Abstract

Ti5SixSb3–x can be prepared by melting mixtures of Ti, Si, and TiSb2. The ternary phase with x = 1.32(5) crystallizes in the W5Si3 type (space group I4/mcm, Z = 8, for x = 1.32(5): a = 1034.6(2), c = 515.2(1) pm), while Ti5Sb3 and Ti5Si3 adopt the Yb5Sb3 type and the Mn5Si3 type, respectively. The Si and Sb atoms share two sites in Ti5Si1.32(5)Sb1.68: one site is located within a linear chain with short interatomic bonds, which is almost exclusively occupied by Si (i.e., 92(1)% Si and 8% Sb), whereas the second site, being occupied by 80(2)% Sb and 20% Si, shows no significant interactions between the main group elements. Band structure calculations reveal the new silicide antimonide being metallic as a consequence of partly filled Ti d states. The structure is mainly stabilized by bonding Ti—Sb, Ti—Si, and Si—Si interactions.Key words: titanium, silicide, antimonide, crystal structure, electronic structure, structure and bonding.